/****************************************************************************
 Copyright (c) 2021 Xiamen Yaji Software Co., Ltd.

 http://www.cocos.com

 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated engine source code (the "Software"), a limited,
 worldwide, royalty-free, non-assignable, revocable and non-exclusive license
 to use Cocos Creator solely to develop games on your target platforms. You shall
 not use Cocos Creator software for developing other software or tools that's
 used for developing games. You are not granted to publish, distribute,
 sublicense, and/or sell copies of Cocos Creator.

 The software or tools in this License Agreement are licensed, not sold.
 Xiamen Yaji Software Co., Ltd. reserves all rights not expressly granted to you.

 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 THE SOFTWARE.
****************************************************************************/

#include "primitive/Torus.h"

namespace cc {
IGeometry torus(float radius, float tube, const cc::optional<ITorusOptions> &opts) {
    const uint32_t radialSegments  = opts.has_value() ? opts->radialSegments : 32;
    const uint32_t tubularSegments = opts.has_value() ? opts->tubularSegments : 32;
    const float    arc             = opts.has_value() ? opts->arc : math::PI_2;

    ccstd::vector<float>    positions;
    ccstd::vector<float>    normals;
    ccstd::vector<float>    uvs;
    ccstd::vector<uint32_t> indices;
    const Vec3              minPos(-radius - tube, -tube, -radius - tube);
    const Vec3              maxPos(radius + tube, tube, radius + tube);
    const float             boundingRadius = radius + tube;

    for (uint32_t j = 0; j <= radialSegments; j++) {
        for (uint32_t i = 0; i <= tubularSegments; i++) {
            const float u = static_cast<float>(i) / static_cast<float>(tubularSegments);
            const float v = static_cast<float>(j) / static_cast<float>(radialSegments);

            const float u1 = u * arc;
            const float v1 = v * math::PI_2;

            // vertex
            const float x = (radius + tube * cos(v1)) * sin(u1);
            const float y = tube * sin(v1);
            const float z = (radius + tube * cos(v1)) * cos(u1);

            // this vector is used to calculate the normal
            const float nx = sin(u1) * cos(v1);
            const float ny = sin(v1);
            const float nz = cos(u1) * cos(v1);

            positions.emplace_back(x);
            positions.emplace_back(y);
            positions.emplace_back(z);
            normals.emplace_back(nx);
            normals.emplace_back(ny);
            normals.emplace_back(nz);

            uvs.emplace_back(u);
            uvs.emplace_back(v);

            if ((i < tubularSegments) && (j < radialSegments)) {
                const uint32_t seg1 = tubularSegments + 1;
                const uint32_t a    = seg1 * j + i;
                const uint32_t b    = seg1 * (j + 1) + i;
                const uint32_t c    = seg1 * (j + 1) + i + 1;
                const uint32_t d    = seg1 * j + i + 1;

                indices.emplace_back(a);
                indices.emplace_back(d);
                indices.emplace_back(b);

                indices.emplace_back(d);
                indices.emplace_back(c);
                indices.emplace_back(b);
            }
        }
    }

    IGeometry info;
    info.positions      = positions;
    info.normals        = normals;
    info.uvs            = uvs;
    info.boundingRadius = boundingRadius;
    info.minPos         = minPos;
    info.maxPos         = maxPos;
    info.indices        = indices;
    return info;
}

} // namespace cc
